1. Field of the Invention
This invention relates to production of azido derivatives of pentaerythritol, and is particularly directed to the preparation of diazido and triazido derivatives of pentaerythritol, and to the process for producing same.
2. Description of the Prior Art
Solid propellants are formulated from an oxidizer and fuel together with suitable binders and plasticizers to impart physical integrity. Most highly energetic systems utilize binders and plasticizers containing energetic groups such as nitro (--NO.sub.2), fluorodinitro (FC(NO.sub.2).sub.2 --), difluoroamino (--NF.sub.2), and many others.
Utilization of azido plasticizers has become a reality during the last several years. These azido plasticizers impart additional energy to propellants since each azido group present adds approximately 85 kcal/mole of energy to the system.
In U.S. application Ser. No. 766,459, filed Aug. 19, 1985, titled Polyazido Esters, by the same inventors as the present application and assigned to the same assignee as the present application, there is disclosed and claimed polyazido esters prepared from diazido and triazido derivatives of pentaerythritol. These derivatives include pentaerythritol triazide and pentaerythritol diazido mononitrate.
Heretofore, it has been attempted to prepare diazido and triazido derivatives of pentaerythritol based on the conversion of pentaerythritol to the dichloro and trichloro derivatives, followed by subsequent reaction with sodium azide to give pentaerythritol diazide and pentaerythritol triazide. However, this method for the preparation of the latter two compounds resulted in mixtures of mono, di, tri and tetra-substituted products. Consequently, the synthesis of the respective azido derivatives of pentaerythritol by such process was unsatisfactory.